Ivermectin Instead of Chemotherapy: A Growing Risk Among Oncology Patients

A growing number of patients diagnosed with cancer are requesting or already using ivermectin, an antiparasitic drug commonly used in veterinary medicine and, in humans, for certain parasitic infections. These patients hope the substance may have effects against the disease, although there is no robust clinical evidence to support this. Specialists warn that abandoning standard oncological treatments, such as chemotherapy, can significantly reduce the chances of recovery.

A study based on the analysis of electronic health records of 68 million patients shows that the number of ivermectin prescriptions issued to oncology patients more than doubled between January and July 2025. Interest was highest among white male patients in the southern United States.

Researchers attribute this increase, at least in part, to a viral episode of Joe Rogan's podcast, which was viewed at least 60 million times. In the January 2025 interview, actor Mel Gibson claimed that a combination of ivermectin and benzimidazole – a compound also used in agriculture – had helped cure several cases of cancer among his friends, according to woodtv.com.

Subsequently, other public figures also promoted this experimental treatment. Ron Duguay, a former NHL player in a relationship with former US vice-presidential candidate Sarah Palin, told ABC News that he uses high doses of ivermectin as part of his treatment for stage 4 colon cancer. Although he also underwent chemotherapy, other patients choose to abandon established oncological treatments entirely in favour of ivermectin.

Dr Merry Jennifer Markham, quoted by the American Cancer Society, stated: "More and more frequently, my patients are asking about medications like ivermectin. I'm grateful they ask, because we can have an informed discussion."

The drug is not approved by the US Food and Drug Administration (FDA) for the treatment of any type of cancer, either in humans or animals, and there are no official clinical guidelines recommending it for this purpose.

What doctors say about efficacy and risks

Dr John Mafi, Associate Professor of Medicine at the David Geffen School of Medicine, University of California, Los Angeles, explained to ABC: "It has not been demonstrated in any confirmatory clinical trial, which is the gold standard of evidence we need to know whether a treatment works."

According to the American Cancer Society, high doses of ivermectin can cause seizures, coma, and even death. Dr Skyler Johnson, from the Huntsman Cancer Institute (University of Utah), explained that the dose required to produce any effect in humans would be considered toxic. Lower doses can negatively interfere with chemotherapy, worsening nausea and vomiting.

People who claim the drug cured their cancer may be disregarding the effect of other scientifically proven treatments administered simultaneously. No clinical study has managed to isolate the effect of ivermectin on cancer cells in humans.

Dr Markham added: "As an oncologist, I like to embrace new therapies that are demonstrated through scientific studies to have potential for my patients. But you can't simply take a drug at random and hope that it works."

Nevertheless, in states such as Texas, Arkansas, and Tennessee, ivermectin is available without a prescription, directly from pharmacies.

The situation in Romania

The Romanian National Society of Medical Oncology (SNOMR) issued an official statement at the request of SmartLiving.ro. At the beginning of the year, the Fact Check department of Agence France-Presse (AFP) published an extensive piece debunking the myths circulating online about the therapeutic potential of ivermectin and fenbendazole in cancer.

SNOMR specifies that the aforementioned drugs are veterinary antiparasitic agents intended exclusively for use in animals: "These are available only in veterinary pharmacies, where a medical prescription may not be required for their purchase. Their oral use in humans is not recommended under any circumstances, given that no clinical studies have been conducted to certify their safety and efficacy in treatments intended for humans."

The Society adds: "Although ivermectin is also available in cream form for dermatological use in humans, there is no robust scientific evidence to support its use in cancer treatments. Furthermore, the use of unregistered medicines, without specific indications for oncological treatments, can lead to serious adverse effects and may compromise the patient's health."

SNOMR acknowledges that preclinical research suggests possible beneficial effects of these drugs in cancer therapy, but considers it premature for them to be used effectively in oncological practice, as no conclusive studies on human subjects yet exist. Under these circumstances, oncologists cannot recommend treatments for which no clear scientific data are available.

What the studies cited online actually say

One of the most frequently cited papers is an article published by researchers in 2020. Dr Mihail Pautov says this paper is often misinterpreted: "The cited study is a literature review, meaning scientists looked through the existing literature to see what had been written about ivermectin and cancer. And they themselves state that there are no studies in humans, that there is no representative sample, and that we do not know what it treats."

The doctor draws attention to the fact that even medical studies can be used to spread misinformation: "It is the perfect example of why studies must be interpreted and analysed by doctors and explained by doctors. When a study like this falls into the hands of people with bad intentions, those people claim there is a study showing that ivermectin is effective against cancer."

Dr Irina Anghel highlights: "In the specialist literature, there are preclinical studies investigating possible effects of ivermectin on certain cellular mechanisms involved in oncogenesis. This research, conducted primarily in vitro or on animal models, has suggested potential biological effects on cell proliferation. However, preclinical results cannot be directly extrapolated to use in humans, due to differences in pharmacology, dosage, and biological complexity. To date, there are no high-quality clinical studies demonstrating a therapeutic benefit of ivermectin in cancer, and the substance is not included in current oncological guidelines."